Anti-rotation assemblies for use with fluid valves

ABSTRACT

An example apparatus includes a valve body defining a fluid flow passageway between an inlet and an outlet, a cage disposed in the fluid flow passageway, a plug disposed in the cage, a retainer collar coupled at an end of the plug, where an exterior surface of the retainer collar includes a first engagement surface having a first non-circular cross-section, and an anti-rotation collar coupled at an end of the cage, where the anti-rotation collar has a second engagement surface defining an aperture to receive the retainer collar, where the aperture has a second non-circular cross-section, where the engagement surfaces interact to inhibit rotation of the retainer collar and the plug.

RELATED APPLICATION

This patent arises from a continuation of U.S. application Ser. No.13/362,750, which was filed on Jan. 31, 2012, titled “Anti-RotationAssemblies for Use with Fluid Valves” and is hereby incorporated hereinby reference in its entirety.

FIELD OF THE DISCLOSURE

This patent relates generally to fluid valves and, more particularly, toanti-rotation assemblies for use with fluid valves.

BACKGROUND

Process control systems use a variety of field devices to control and/ormonitor process parameters. Field devices, such as fluid control valves,control the flow of fluid through a passageway of a valve. A controlvalve typically employs an actuator to move a flow control memberrelative to an orifice of the valve to allow fluid flow through thepassageway of the valve and to restrict or prevent fluid flow throughthe passageway of the valve. The actuator is operatively coupled to theflow control member via a valve stem.

Some process control devices often include seals to prevent fluidleakage. For example, some known fluid valves employ a bellows-type sealto prevent fluid leakage to the environment along the valve stem.However, the seals (e.g., bellows seals) are often subjected to stressesduring operation that can significantly reduce the operating life of theseal. For example, fluid flowing through the passageway of the valvebody may impart torsion loads to a bellows-type seal. Such torsion loadsmay significantly reduce the cycle life of the bellows-type seal.

SUMMARY

An example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage disposed in the fluidflow passageway, a plug disposed in the cage, a retainer collar coupledat an end of the plug, where an exterior surface of the retainer collarincludes a first engagement surface having a first non-circularcross-section, and an anti-rotation collar coupled at an end of thecage, where the anti-rotation collar has a second engagement surfacedefining an aperture to receive the retainer collar, where the aperturehas a second non-circular cross-section, where the engagement surfacesinteract to inhibit rotation of the retainer collar and the plug.

Another example apparatus includes a first collar to be coupled to aplug, where an exterior surface of the first collar has a first keyedsurface, and where an interior surface of the first collar at leastpartially surrounds the plug, and a second collar to be coupled to acage, where the second collar defines an aperture, and where theaperture is at least partially defined by a second keyed surface, wherethe second collar is to receive the first collar, and where the firstkeyed surface to interact with the second keyed surface to inhibitrotation of the first collar relative to the second collar.

Another example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage to be disposed in thefluid flow passageway, where the cage includes an interior surfacedefining an aperture having a first non-circular cross-section, and aplug disposed in the aperture of the cage, where an exterior surface ofthe plug defines a second non-circular cross-section corresponding tothe first non-circular cross-section, and where an interaction betweenthe first and second non-circular cross-sections prevents rotation ofthe plug relative to the cage.

Another example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage, a plug disposed inthe cage, a plug collar coupled at an end of the plug, where an exteriorsurface of the plug collar has a first non-circular cross-section, and acage collar coupled at an end of the cage, where the cage collar definesan aperture having a second non-circular cross-section, the plug collardisposed in the aperture, and where an engagement between the exteriorsurface of the plug collar and an interior surface defining the apertureto prevent rotation of the plug as the plug moves relative to a valveseat to control fluid flow between the inlet and the outlet.

Another example apparatus includes a valve body defining a flowaperture, a cage disposed within the flow aperture, a plug movablerelative to the flow aperture to control fluid flow through the valve,where the plug is slidably guided by the cage throughout a stroke of thevalve, and means for preventing rotation of the plug relative to alongitudinal axis of the valve, where the means for preventing rotationis disposed at an end of the plug and an end of the cage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a known fluid valve.

FIG. 2 is a cross-sectional view of an anti-rotation retainer assemblythat may be used with the fluid valve of FIG. 1.

FIG. 3A is a cross-sectional, perspective view of the exampleanti-rotation assembly of FIG. 2.

FIG. 3B is a plan view of the example anti-rotation assembly of FIGS. 2and 3A.

DETAILED DESCRIPTION

Example anti-rotation assemblies disclosed herein significantly reduceor prevent twisting rotation of a valve stem and/or a flow controlmember relative to a valve body of a fluid valve. As a result, theanti-rotation assemblies disclosed herein may be used to prevent orsignificantly reduce torsional loads imparted to a bellows-type seal.For example, the anti-rotation assemblies disclosed herein significantlyprevent a process fluid (e.g., a relatively high pressure process fluid)flowing through a passageway of a valve from twisting or turning a flowcontrol member and/or a valve stem relative to a longitudinal axis ofthe flow control member when the flow control member is positioned awayfrom a valve seat of the fluid valve. Limiting rotation of the valvestem and/or the flow control member significantly extends an operatinglife of a bellows-type seal.

Additionally or alternatively, the example anti-rotation assembliesdisclosed herein enable use of a balanced flow control member. Inparticular, the anti-rotation assemblies disclosed herein define a sealgland to receive a seal that prevents fluid flow or leakage between theflow control member and a cage and/or a valve body when the flow controlmember is in a closed position. A balanced flow control member requiresless thrust to move between an open position and a closed position. As aresult, a relatively smaller actuator may be employed.

An example anti-rotation assembly disclosed herein includes ananti-rotation retainer and an anti-rotator. The anti-rotation retaineris coupled (e.g., fixed) to a flow control member. The anti-rotationretainer includes an opening to receive at least a portion of a flowcontrol member or valve plug (e.g., a balanced valve plug) and an outersurface defining a first engaging surface or keyed portion. Also, atleast a portion of the anti-rotator also includes an engaging surface orkeyed portion. The engaging surface or keyed portion of the anti-rotatoris complementary to the engaging surface or keyed portion of theanti-rotation retainer to provide a substantially tight fit connectionbetween the anti-rotator and the anti-rotation retainer when theanti-rotator is coupled to the anti-rotation retainer.

When coupled to a fluid valve, the anti-rotator engages theanti-rotation retainer to prevent the anti-rotation retainer and, thus,the flow control member from rotating or twisting relative to alongitudinal axis of the anti-rotation retainer and/or the flow controlmember. In some examples, the engaging surface of the anti-rotationretainer may be formed along a portion of an outer surface of theanti-rotation retainer and the engaging surface of the anti-rotator maybe formed along a portion of an inner surface of the anti-rotator. Therespective engaging surfaces of the anti-rotator and the anti-rotationretainer may be one or more substantially flat-shaped or straightsurfaces.

Before discussing an example anti-rotation assembly disclosed herein, abrief description of a known fluid valve 100 is provided in FIG. 1. Thefluid valve 100 of FIG. 1 includes a valve body 102 defining a fluidflow passageway 104 between an inlet 106 and an outlet 108. A flowcontrol assembly 110 controls fluid flow through the passageway 104. Asshown in FIG. 1, the flow control assembly 110 includes a valve plug112, a cage 114, a valve stem 116, an anti-rotator 118, and a bellowsseal flange 120.

The valve plug 112 is operatively coupled to the valve stem 116 andmoves in a first direction away from a valve seat 122 to allow fluidflow through the passageway 104 and moves in a second direction towardthe valve seat 122 to restrict or prevent fluid flow through thepassageway 104. The valve plug 112 of FIG. 1 is an unbalanced valveplug. Thus, a relatively large actuator may be required to move thevalve plug 112 to a closed position and/or provide sufficient thrust tothe valve plug 112 to provide a relatively tight seal when valve plug112 sealingly engages the valve seat 122 in a closed position. A bonnetextension 124 couples the valve body 102 to a bonnet 126, which couplesthe valve body 102 to an actuator (not shown).

In FIG. 1, the bonnet extension 124 includes an aperture 128 to slidablyreceive the valve stem 116. In addition, a bellows seal 130 is disposedwithin the aperture 128 of the bonnet extension 124 to prevent fluid ina chamber 132 of the valve body 102 from leaking to the environmentalong the valve stem 116. As shown, the bellows seal 130 has a first end134 a coupled to the bellows seal flange 120 and a second end 134 bcoupled to an upper portion or connector 136 of a bellows tubing 130 a.The connector 136 is coupled to the bellows tubing 130 a via, forexample, welding, and includes a central aperture to slidably receivethe valve stem 116. The bellows tubing 130 a is coupled to the bellowsflange 120 via, for example, welding.

In operation, an actuator (not shown) moves the valve plug 112 relativeto the valve seat 122 in a rectilinear motion along a longitudinal axis140 to control the fluid flow through the passageway 104. In addition,the bellows seal 130 compresses and expands axially in a direction alongthe longitudinal axis 140 when the valve stem 116 moves between a firstposition at which the valve plug 112 sealingly engages the valve seat122 and a second position at which the valve plug 112 is away from thevalve seat 122 (e.g., an open position). Thus, during each operationalcycle, the bellows seal 130 is subjected to a load (e.g., an axial load)and, thus, a stress which affects the cycle-life and/or useful life ofthe bellows seal 130.

The bellows seal 130 has one or more convolutions 142 that axiallycompress or expand along the longitudinal axis 140 depending upon themovement of valve stem 116. To form the convolutions 142, the bellowsseal 130 is formed or stamped from rolling a flat sheet or foil into atube which is then longitudinally fusion welded. Alternatively, the seal130 may be formed by welding washer-like plates of thin metal togetherat both the inner and outer circumference of the washers. The weldedportions of the convolutions are susceptible to damage when torsionalloads (e.g., relatively large torsional loads or forces) are imparted tothe bellows seal 130. In some examples, the torsional loads may causethe bellows seal 130 to fail prior to a rated cycle-life of the bellowsseal 130 (e.g., an operating life of a bellows seal that is notsubjected to torsional loads).

For example, during operation, a relatively high pressure process fluidmay impart a torsional load on the valve plug 112 when the valve plug112 is away from the valve seat 122. Because the valve stem 116 isfixedly coupled to the valve plug 112 at the first end 134 a, thetorsion load imparted to the valve plug 112 causes the valve stem 116 totwist or turn relative to the longitudinal axis 140. In turn, the firstend 134 a between the bellows seal 130 and the valve stem 116 causes thebellows seal 130 to experience a torsional load. During operation, theanti-rotator 118 reduces rotational movement of the valve plug 112relative to the longitudinal axis 140, which reduces such twisting ofthe bellows seal 130. However, as noted above, the valve plug 112 is anunbalanced valve plug. Employing a balanced valve plug in combinationwith the anti-rotator 118 of FIG. 1 may affect (e.g., reduce) a shut-offclassification of the fluid valve 100 because fluid leakage may occurbetween the cage 114 and the valve plug 112 when the valve plug 112 issealingly engaged with the valve seat 122 (e.g., in a closed position).

FIG. 2 is a cross-sectional view of an example fluid valve 200 having aflow control assembly 202 that includes an example anti-rotationassembly 204 in accordance with the teachings disclosed herein. Forexample, the flow control assembly 202 and/or the anti-rotation assembly204 may replace the flow control assembly 110 of FIG. 1 and/or mayretrofit a fluid valve in the field such as, for example, the fluidvalve 100 of FIG. 1.

Referring to FIG. 2, the fluid valve 200 includes a valve body 206defining a fluid flow passageway 208 between an inlet 210 and an outlet212. The flow control assembly 202 is disposed within the passageway 208to control fluid flow through the passageway 208 between the inlet 210and the outlet 212. The flow control assembly 202 of FIG. 2 includes aflow control member 214 (e.g., a valve plug), a cage 216 and theanti-rotation assembly 204. More specifically, the cage 216 includes anopening 218 to slidably receive at least a portion of the flow controlmember 214 and is disposed between the inlet 210 and the outlet 212 toimpart certain flow characteristics to the fluid flowing through thepassageway 208 (e.g., to control capacity, reduce noise, reducecavitation, etc.).

As shown in FIG. 2, the flow control member 214 includes a sealingsurface 220 that engages a valve seat 222 integrally formed with thecage 216 when the flow control member 214 sealingly engages the valveseat 222 (e.g., a closed position). Thus, the flow rate permittedthrough the fluid valve 200 is controlled by the position of the flowcontrol member 214 relative to the valve seat 222.

The flow control member 214 is a balanced flow control member andincludes a central opening 224 to receive (e.g., threadably receive) avalve stem 226. To further prevent rotation of the flow control member214 relative to the valve stem 226, the flow control member 214 includesan opening 228 to receive a fastener or pin (not shown). To balance theflow control member 214, a plurality of through passageways 232 isformed between an upper surface 234 and a lower surface 236 of the flowcontrol member 214. Each of the passageways 232 includes an axis 232 athat is substantially parallel to a longitudinal axis 230 of the flowcontrol member 214 and enables fluid flow between the lower and uppersurfaces 234 and 236 of the flow control member 214. As a result of thebalanced flow control member 214 and in contrast to the fluid valve 100of FIG. 1, a relatively smaller actuator providing less thrust may beemployed to move the flow control member 214 between an open positionand a closed position and/or to move the flow control member 214 intosealing engagement with the valve seat 222 to prevent or restrict fluidflow through the passageway 208. The fluid valve 200 of FIG. 2 alsoincludes a bellows seal 238 that surrounds the valve stem 226 to preventleakage of process fluid to the environment along the valve stem 226.

The anti-rotation assembly 204 is disposed in the passageway 208 of thevalve body 206. The example anti-rotation assembly 204 includes ananti-rotation retainer, insert or guide 240 and an anti-rotator 242. Theanti-rotation retainer 240 of FIG. 2 is at least partially disposed inthe opening 218 of the cage 216 and the anti-rotator 242 is disposed orcaptured between the cage 216 and a bellows seal flange 244. In otherexamples, the cage 216 may be omitted such that the anti-rotator 242 isdisposed or captured between the bellows seal flange 244 and the valvebody 206. The bellows seal 238 is coupled to the valve stem 226 at afirst end and is coupled to a connector such as, for example, theconnector 136 of FIG. 1 at a second end of the bellows seal 238 oppositethe first end. The anti-rotation assembly 204 prevents or significantlyreduces torsional loads from being imparted to the bellows seal 238.

The anti-rotation retainer 240 of the illustrated example includes afirst portion or body 246 (e.g., a cylindrical body) and a secondportion or flange 248. The body 246 defines a first outer surfaceportion 250 of the anti-rotation retainer 240 and the flange 248 definesa second outer surface portion 252 of the anti-rotation retainer 240. Asshown in FIG. 2, a diameter or size of the flange 248 is greater than adiameter of the body 246. More specifically, the body 246 is at leastpartially disposed in the opening 218 of the cage 216 and/or slidesrelative to an inner surface 254 of the opening 218 of cage 216.

As shown in FIG. 2, an end or edge 256 of the body 246 of theanti-rotation retainer 240, the cage 216 and the flow control member 214define a gland or cavity 258 to receive a seal 260 (e.g., a C-seal) thatprevents fluid leakage between the anti-rotation retainer 240 and thecage 216 when the flow control member 214 is in sealing engagement withthe valve seat 222. In other examples, however, the body 246 of theanti-rotation retainer 240 and/or the flange 248 may include a groove orchannel (e.g., an annular gland) to receive the seal 260. Additionallyor alternatively, the outer surface portion 250 defined by the body 246of the anti-rotation retainer 240 includes an annular gland 262 toreceive a piston ring 264 (e.g., a carbon-graphite piston ring) to helpmaintain alignment of the anti-rotation retainer 240 relative to thecage 216 and/or helps to provide a seal between the anti-rotationretainer 240 and the cage 216. In some examples, the annular gland 262may receive a seal (e.g., a C-seal).

FIG. 3A is a cross-sectional perspective view of the anti-rotationassembly 204 of FIG. 2. FIG. 3B is a plan view of the anti-rotationretainer 240 coupled to the flow control member 214. Referring to FIGS.3A and 3B, the anti-rotation retainer 240 is a cylindrical body 302having a central opening 304 that is sized or configured to receive atleast a portion 306 (e.g., a stem portion) of the flow control member214. In addition, the flow control member 214 is fixedly coupled to theanti-rotation retainer 240. As shown in FIG. 3A, the anti-rotationretainer 240 includes one or more openings 308 that align withrespective openings 310 of the flow control member 214. An opening 308 aof the anti-rotation retainer 240 and an opening 310 a of the flowcontrol member 214 receive a pin 312 to couple (e.g., fixedly couple)the anti-rotation retainer 240 and the flow control member 214 such thatthe flow control member 214 cannot move (e.g., rotate or slide) relativeto the anti-rotation retainer 240. The openings 308 of the anti-rotationretainer 240 are formed between an inner surface 314 of the body 246 andan annular surface 316 that is formed or defined by the annular gland262 of the body 246. In this example, the openings 308 and 310 includerespective axes 318 that are substantially perpendicular to thelongitudinal axis 230. In other examples, however, the respective axes318 of the openings 308 and 310 may be at any angle and/or non-parallelorientation relative to the longitudinal axis 230. Thus, the valve stem226, the flow control member 214 and the anti-rotation retainer 240 arefixedly coupled to function as a unitary unit or assembly.

In the illustrated example, the anti-rotation retainer 240 defines anengaging surface or keyed portion 320 of the anti-rotation retainer 240.The engaging surface or keyed portion 320 is formed along at least aportion of the outer surfaces 250 and/or 252 of the anti-rotationretainer 240. In particular, the engaging surface 320 as shown in FIG.3A is disposed or formed in proximity to or adjacent an outer peripheraledge of the flange 248. More specifically, the engaging surface 320 ofthe illustrated example includes one or more substantially flat-shapedor straight portions or surfaces 324. As most clearly shown in FIG. 3B,the substantially flat-shaped portions 324 are disposed between arcuateor curved surfaces 326 of the anti-rotation retainer 240 or the flange248. For example, the anti-rotation retainer 240 may be formed as acylindrical body and the substantially flat-shaped portions 324 may beformed subsequently via, for example, machining.

The anti-rotator 242 is a cylindrical body 330 having a central opening332. In particular, the central opening 332 defines an inner surface 334having at least a stepped portion 336. Similar to the anti-rotationretainer 240, the anti-rotator 242 includes an engaging surface or keyedportion 338. More specifically, engaging surface 338 is formed along atleast a portion of the inner surface 334 of the anti-rotator 242. In theillustrated example, the engaging surface 338 of the anti-rotator 242includes one or more substantially flat-shaped or straight surfaces orportions 340. As shown in FIG. 3A, the one or more substantiallyflat-shaped portions 340 of the anti-rotator includes a wall orprojection 342 formed on the inner surface 334 that projects toward thelongitudinal axis 230 where the wall 342 defines the substantiallyflat-shaped portion 340. In this example, the anti-rotator 242 includestwo substantially flat-shaped portions 340 a and 340 b radially spacedapproximately 180 degrees relative to the longitudinal axis 230.However, in other examples, the anti-rotator 242 may include only onesubstantially flat-shaped portion 340 or engaging surface 338 and/ormore than two flat-shaped portions 340 or engaging surfaces 338 disposedon the inner surface 334 of the anti-rotator 242. As shown, the engagingsurfaces 338 and/or walls 342 are formed between arcuate or curvedsurfaces 344 of the inner surface 334 of the anti-rotator 242.

The engaging surface 320 of the anti-rotation retainer 240 engages orcontacts (e.g., directly contacts) the engaging surface 338 of theanti-rotator 242. In the illustrated example, both the substantiallyflat-shaped surfaces 324 and 340 of the respective anti-rotationretainer 240 and the anti-rotator 242 have faces or planes that aresubstantially parallel to the longitudinal axis 230. In addition, theanti-rotation retainer 240 can slide relative to the anti-rotator 242when the flow control member 214 moves relative to the valve seat 222between the open position and the closed position. In other examples,the engaging surfaces 320 and 338 of the respective anti-rotationretainer 240 and the anti-rotator 242 may have different shapes orconfigurations other than the substantially flat-shaped surfaces 324 and340 described in FIGS. 3A and 3B. For example, the wall 342 may includea track and/or a slot that engages or slides relative to a complementaryslot and/or track formed on the flange 248 of the anti-rotation retainer240 (e.g., a tongue-and-groove connection). In yet other examples, theengaging surface 320 of the anti-rotation retainer 240 and the engagingsurface 338 of the anti-rotator 242 may be a splined connection. Forexample, the engaging surfaces 320 and 338 may include splines thatextend along an entire circumference or perimeter of the anti-rotationretainer 240 and the anti-rotator 242.

In operation, when coupled to the anti-rotation retainer 240, theanti-rotator 242 prevents rotation of the anti-rotation retainer 242and, thus, the flow control member 214 relative to the longitudinal axis230 (i.e., the anti-rotation retainer 240 and/or the cage 216). Inparticular, the engaging surface 320 of the anti-rotation retainer 240is complementary to the engaging surface 338 of the anti-rotator 242 toprovide a substantially tight fit connection between the anti-rotator242 and the anti-rotation retainer 240. More specifically, thesubstantially flat-shaped portions 324 and 340 of the respectiveanti-rotation retainer 240 and the anti-rotator 242 engage to preventrotation of the anti-rotation retainer 240 relative to the longitudinalaxis 230 when the anti-rotation retainer 240 is disposed within thefluid valve 200. Thus, the flow control member 214, via theanti-rotation assembly 204, prevents twisting or torsional loads appliedto the flow control member 214 from being conveyed to the bellows seal238, thereby increasing the operating life of the bellows seal 238.

As set forth herein, an example anti-rotation assembly includes ananti-rotation retainer to couple to a flow control member of a valve,and an anti-rotator to engage the anti-rotation retainer, where theanti-rotator is to prevent rotation of the anti-rotation retainerrelative to a longitudinal axis of the anti-rotation retainer when theanti-rotation retainer is disposed in the valve.

In some examples, the anti-rotator includes a first engaging surface toengage a second engaging surface of the anti-rotation retainer. In somesuch examples, the first engaging surface of the anti-rotator iscomplementary to the second engaging surface of the anti-rotationretainer. In such some examples, the first engaging surface is formedalong at least a portion of an inner surface of the anti-rotator and thesecond engaging surface is formed along at least a portion of an outersurface of the anti-rotation retainer. In some examples, the firstengaging surface and the second engaging surface each includes one ormore substantially flat-shaped portions. In some examples, theanti-rotator includes a cylindrical body having a central opening todefine the inner surface, where the inner surface has the one or moresubstantially flat-shaped portions. In some examples, at least one ofthe substantially flat-shaped portions of the anti-rotator includes awall projecting toward the longitudinal axis, where the wall defines thesubstantially flat-shaped portions. In some examples, the anti-rotatorincludes two substantially flat-shaped portions radially spacedapproximately 180 degrees relative to the longitudinal axis. In someexamples, the one or more substantially flat-shaped surfaces of theanti-rotation retainer are disposed between arcuate surfaces. In someexamples, the anti-rotation retainer includes a cylindrical body and aflange, where the flange defines the second engaging surface and thebody defines an outer surface portion adjacent the flange. In someexamples, the second engaging surface of the anti-rotation retainer hasa diameter that is greater than a diameter of the outer surface portion.In some examples, the anti-rotation retainer includes a central openingto receive at least a portion of the flow control member. In someexamples, the anti-rotation assembly further includes a cage having anopening to slidably receive at least a portion of the anti-rotationretainer and the flow control member. In some examples, theanti-rotation assembly further includes a seal, where the anti-rotationretainer is to retain the seal in the valve. In some examples, the sealis disposed between an edge of the anti-rotation retainer, the flowcontrol member and the cage.

An example anti-rotation assembly includes an anti-rotation retainerhaving an opening to receive at least a portion of a balanced valve plugand an outer surface defining a first engaging surface and ananti-rotator having a central opening defining an inner surface, wherethe inner surface has a second engaging surface, and the first engagingsurface is complementary to the second engaging surface, where the firstengaging surface is to engage the second engaging surface when theanti-rotation retainer is coupled to the anti-rotator to preventrotation of the anti-rotation retainer relative to the anti-rotator.

In some examples, the first engaging surface includes one or moresubstantially flat-shaped surfaces disposed along a portion of the outersurface of the anti-rotation retainer and the second engaging surfaceincludes one or more substantially flat-shaped surfaces formed along aportion of the inner surface of the anti-rotator. In some examples, theanti-rotation assembly further includes a balanced valve plug coupled tothe anti-rotation retainer via a pin such that rectilinear movement ofthe balanced valve plug relative to a longitudinal axis of theanti-rotation retainer causes the anti-rotation retainer to move withthe balanced valve plug. In some examples, the anti-rotation assemblyfurther includes a cage having a central opening to slidably receive atleast a portion anti-rotation retainer and the balanced valve plug.

Another example rotation assembly includes means for retaining a flowcontrol member of a valve, the means for retaining to be disposed in avalve, the means for retaining having first means for engaging and meansfor preventing rotation of the means for retaining, the means forretaining having second means for engaging, the first means for engagingto engage the second means for engaging to prevent rotation of the meansfor retaining relative to the means for preventing rotation relative toa longitudinal axis of the means for retaining.

Another example ant-rotation assembly includes a cage to be disposedinside a valve body, where the cage defines a first aperture having asubstantially circular cross-section, a plug disposed within the firstaperture of the cage throughout a stroke of the valve, where aninteraction between the plug and the first aperture to guide movement ofthe plug throughout the stroke of the valve, the plug having asubstantially circular cross-section, an anti-rotation retainer coupledto the plug, where the anti-rotation retainer has an exterior surfacedefining a non-circular cross-section and an interior surface at leastpartially surrounding the plug, an anti-rotator coupled to an end of thecage, where the anti-rotator defines a second aperture having anon-circular cross-section, and where an engagement between theanti-rotator and the exterior surface to reduce rotation of theanti-rotation retainer and the plug relative to a longitudinal axis ofthe anti-rotation retainer, a seal coupled to at least one of the plugor the anti-rotation retainer, where the seal is to sealingly engage thecage to substantially prevent fluid flow between the seal and the cage,and a transverse bore extending through the anti-rotation retainer andthe plug, where a fastener is to be disposed in the transverse bore tocouple the plug and the anti-rotation retainer, and where theanti-rotation retainer defines an opening of the transverse bore, wherethe anti-rotation retainer defines a groove into which the seal isdisposed, and where the transverse bore intersects the groove at theopening of the transverse bore.

In some examples, the seal is to cover the opening of the transversebore. In some examples, the anti-rotation assembly further includes asecond transverse bore extending through the anti-rotation retainer andthe plug, where a second fastener is to be disposed in the secondtransverse bore to couple the plug and the anti-rotation retainer, andwhere the anti-rotation retainer defining an opening of the secondtransverse bore. In some such examples, the first and second transversebores are disposed along a transverse axis of the anti-rotationretainer. In some examples, the example anti-rotation assembly includesa stem to be coupled within an aperture of the plug. In some examples,the anti-rotator includes a first engaging surface to engage a secondengaging surface of the exterior surface of the anti-rotation retainer.In some examples, the first engaging surface of the anti-rotator iscomplementary to the second engaging surface of the anti-rotationretainer. In some examples, the first engaging surface is formed alongat least a portion of the interior surface of the anti-rotator and thesecond engaging surface is formed along at least a portion of theexterior surface of the anti-rotation retainer.

In some examples, wherein each of the first engaging surface and thesecond engaging surface includes a substantially flat-shaped portion. Insome examples, the anti-rotator includes a cylindrical body having thesecond aperture that defines the interior surface, where the interiorsurface has the substantially flat-shaped portion. In some examples, thesubstantially flat-shaped portion of the anti-rotator includes a wallprojecting toward the longitudinal axis, where the wall defines thesubstantially flat-shaped portion. In some examples, the anti-rotatorincludes two substantially flat-shaped portions radially spacedapproximately 180 degrees relative to the longitudinal axis. In someexamples, the substantially flat-shaped portion of the anti-rotationretainer is disposed between arcuate surfaces. In some examples, theanti-rotation retainer includes a cylindrical body and a flange, wherethe flange defines the second engaging surface and the body defining anouter surface portion adjacent the flange. In some examples, the secondengaging surface of the anti-rotation retainer has a diameter that isgreater than a diameter of the outer surface portion. In some examples,the anti-rotation retainer includes a central opening to receive atleast a portion of the plug. In some examples, the cage is to slidablyreceive at least a portion of the anti-rotation retainer.

In some examples, an interaction between the seal and the groove is toretain the seal relative to the anti-rotation retainer and the plug. Insome examples, the seal is disposed at an interface between theanti-rotation retainer and the plug. In some examples, the exteriorsurface of the anti-rotation retainer defines a first keyed surface, thesecond aperture of the anti-rotator defines a second keyed surface,where the anti-rotator is to be disposed within the valve, and where theanti-rotator is to receive the plug and the anti-rotation retainer,where the first keyed surface is to engage the second keyed surface toreduce rotation of the anti-rotation retainer relative to theanti-rotator, and the seal surrounds the plug, where the seal isdisposed at an interface between the plug and the anti-rotationretainer. In some examples, the first keyed surface includes one or moresubstantially flat-shaped surfaces disposed along a portion of theexterior surface of the anti-rotation retainer and the second keyedsurface includes one or more substantially flat-shaped surfaces formedalong a portion of an inner surface of the anti-rotator. In someexamples, the fastener includes a pin to cause the anti-rotationretainer to move with the plug throughout a stroke of the valve. In someexamples, the first aperture of the cage is to slidably guide theanti-rotation retainer and the plug, where an interaction between theseal and the cage is to substantially prevent fluid flow between theseal and the cage.

In some examples, the anti-rotation assembly includes a valve bodydefining a flow aperture, where the cage is disposed within the flowaperture, where the plug is movable relative to the flow aperture tocontrol fluid flow through the valve, where the anti-rotation retaineris directly coupled to the plug and the anti-rotator is directly coupledto the cage, and the seal is disposed between at least one of the cageand the anti-rotation retainer or the anti-rotator. In some examples,the seal surrounds a collar of the plug, where the seal is disposed atan interface between the plug and the anti-rotation retainer. In someexamples, the seal is to be loaded into engagement with an inner surfaceof the cage to substantially prevent fluid flow between at least one ofthe plug or the anti-rotation retainer and the cage. In some examples,the plug comprises a balanced plug. In some examples, the anti-rotationassembly includes a second seal coupled to the plug or the anti-rotationretainer to substantially prevent fluid flow between the second seal andthe cage. In some examples, a portion of the plug defining thetransverse bore comprises a blind hole.

Another example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage disposed in the fluidflow passageway, a plug disposed in the cage, a retainer collar coupledat an end of the plug, where an exterior surface of the retainer collarincludes a first engagement surface having a first non-circularcross-section, and an anti-rotation collar coupled at an end of thecage, where the anti-rotation collar has a second engagement surfacedefining an aperture to receive the retainer collar, where the aperturehas a second non-circular cross-section, where the engagement surfacesinteract to inhibit rotation of the retainer collar and the plug.

In some examples, the retainer collar includes a first transverse boreand the plug includes a second transverse bore, where a fastener isdisposed in the first and second transverse bores to couple the plug andthe retainer collar. In some examples, the retainer collar defines agroove into which a seal is to be disposed, where the first transversebore intersects the groove at an opening of the first transverse bore.In some examples, an interaction between the seal and the groove is toretain the seal relative to the retainer collar and the plug. In someexamples, the seal is to cover the opening of the first transverse bore.In some examples, the first engagement surface and the second engagementsurface include corresponding flat surfaces that interact to inhibitrotation of the retainer collar relative to the anti-rotation collar. Insome examples, the first engagement surface or the second engagementsurface includes splines and the other of the first engagement surfaceor the second engagement surface includes grooves to receive the splinesto inhibit rotation of the retainer collar relative to the anti-rotationcollar. In some examples, the first engagement surface or the secondengagement surface includes a slot and the other of the first engagementsurface or the second engagement surface includes a protrusion to bereceived by the slot to inhibit rotation of the retainer collar relativeto the anti-rotation collar. In some examples, the retainer collarincludes a cylindrical body and a flange extending from the cylindricalbody, where the flange defines the first engagement surface. In someexamples, an exterior surface of the cylindrical body is flush with anexterior surface of the plug. In some examples, the plug includes astep, where an end of the retainer collar is received in the step. Insome examples, the aperture is a first aperture, where the retainercollar including a second aperture to receive the end of the plug. Insome examples, a third aperture is defined by the plug, where the secondand third apertures are coaxial, and where the third aperture receives astem and the second aperture to surround the stem.

Another example apparatus includes a first collar to be coupled to aplug, where an exterior surface of the first collar has a first keyedsurface, and where an interior surface of the first collar at leastpartially surrounds the plug, and a second collar to be coupled to acage, where the second collar defines an aperture, and where theaperture is at least partially defined by a second keyed surface, wherethe second collar is to receive the first collar, and where the firstkeyed surface to interact with the second keyed surface to inhibitrotation of the first collar relative to the second collar.

In some examples, the second collar to be disposed within a fluidpassageway of a valve. In some examples, the first keyed surfaceincludes one or more substantially flat surfaces and the second keyedsurface includes one or more substantially flat surfaces. In someexamples, a pin is disposed in a first transverse bore of the firstcollar and a second transverse bore of the plug, where the pin is tocouple the first collar and the plug. In some examples, the cage definesa second aperture to receive and slidably guide the plug, where aninteraction between a seal and the cage substantially prevents fluidflow between the seal and the cage and to align the first collarrelative to the cage. In some examples, the first keyed surface includesopposing first flat surfaces to engage respective opposing second flatsurfaces of the second keyed surface, where the opposing first andsecond surfaces inhibit rotation of the first collar relative to thesecond collar. In some examples, the second collar includes an internalflange defining the second keyed surface.

Another example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage to be disposed in thefluid flow passageway, where the cage includes an interior surfacedefining an aperture having a first non-circular cross-section, and aplug disposed in the aperture of the cage, where an exterior surface ofthe plug defines a second non-circular cross-section corresponding tothe first non-circular cross-section, and where an interaction betweenthe first and second non-circular cross-sections prevents rotation ofthe plug relative to the cage.

In some examples, the plug includes a first portion and a secondportion, where the first portion at least partially surrounds the secondportion and defines the second non-circular cross-section, and where thesecond portion receives a stem. In some examples, the cage includes afirst portion and a second portion, where the first portion defines theaperture having the first non-circular cross-section, and the secondportion receives the plug.

Another example apparatus includes a valve body defining a fluid flowpassageway between an inlet and an outlet, a cage, a plug disposed inthe cage, a plug collar coupled at an end of the plug, where an exteriorsurface of the plug collar has a first non-circular cross-section, and acage collar coupled at an end of the cage, where the cage collar definesan aperture having a second non-circular cross-section, the plug collardisposed in the aperture, and where an engagement between the exteriorsurface of the plug collar and an interior surface defining the apertureto prevent rotation of the plug as the plug moves relative to a valveseat to control fluid flow between the inlet and the outlet.

In some examples, the plug collar includes a flange, where the flangehas a first keyed surface corresponding to a second keyed surface of thecage collar, and where the second keyed surface is disposed in theaperture. In some examples, the first keyed surface and the second keyedsurface include interacting flat structures to prevent rotation of theplug collar relative to the cage collar. In some examples, the plugcollar includes a first transverse bore to intersect a second transversebore of the plug, where a fastener is disposed in the first transversebore to enable the plug and plug collar to move together relative to thecage and cage collar. In some examples, an opening of the firsttransverse bore defines a groove surrounding the plug collar, where aseal is disposed within the groove to prevent fluid flow between thecage and the plug collar. In some examples, the aperture is a firstaperture and the plug includes a second aperture, where the first andsecond apertures are coaxial, and where a stem is received within thesecond aperture, where the first aperture surrounds the stem.

Another example apparatus includes a valve body defining a flowaperture, a cage disposed within the flow aperture, a plug movablerelative to the flow aperture to control fluid flow through the valve,where the plug is slidably guided by the cage throughout a stroke of thevalve, and means for preventing rotation of the plug relative to alongitudinal axis of the valve, where the means for preventing rotationis disposed at an end of the plug and an end of the cage. In someexamples, the means for preventing rotation includes first and secondcorresponding keyed surfaces that interact to prevent rotation of theplug relative to the cage. In some examples, the plug is coupled to aretainer collar including the first keyed surface and the cage iscoupled to an anti-rotation collar including the second keyed surface.

Although certain example methods, apparatus and articles of manufacturehave been described herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe appended claims either literally or under the doctrine ofequivalents.

What is claimed is:
 1. An apparatus comprising: a valve body defining afluid flow passageway between an inlet and an outlet; a cage disposed inthe fluid flow passageway; a plug disposed in the cage; a retainercollar coupled at an end of the plug, the retainer collar includes afirst transverse bore and the plug includes a second transverse bore, afastener disposed in the first and second transverse bores to couple theplug and the retainer collar, an exterior surface of the retainer collarincluding a first engagement surface having a first non-circularcross-section; and an anti-rotation collar coupled at an end of thecage, the anti-rotation collar having a second engagement surfacedefining an aperture to receive the retainer collar, the aperture havinga second non-circular cross-section, the engagement surfaces to interactto inhibit rotation of the retainer collar and the plug, the retainercollar defines a groove into which a seal is to be disposed, the firsttransverse bore intersects the groove at an opening of the firsttransverse bore.
 2. The apparatus of claim 1, wherein an interactionbetween the seal and the groove is to retain the seal relative to theretainer collar and the plug.
 3. The apparatus of claim 1, wherein theseal is to cover the opening of the first transverse bore.
 4. Theapparatus of claim 1, wherein the first engagement surface and thesecond engagement surface include corresponding flat surfaces thatinteract to inhibit rotation of the retainer collar relative to theanti-rotation collar.
 5. The apparatus of claim 1, wherein the firstengagement surface or the second engagement surface includes splines andthe other of the first engagement surface or the second engagementsurface includes grooves to receive the splines to inhibit rotation ofthe retainer collar relative to the anti-rotation collar.
 6. Theapparatus of claim 1, wherein the first engagement surface or the secondengagement surface includes a slot and the other of the first engagementsurface or the second engagement surface includes a protrusion to bereceived by the slot to inhibit rotation of the retainer collar relativeto the anti-rotation collar.
 7. The apparatus of claim 1, wherein theaperture is a first aperture, the retainer collar including a secondaperture to receive the end of the plug.
 8. The apparatus of claim 7,further including a third aperture defined by the plug, the second andthird apertures being coaxial, the third aperture to receive a stem andthe second aperture to surround the stem.
 9. The apparatus of claim 1,wherein the retainer collar includes a cylindrical body and a flangeextending from the cylindrical body, the flange defining the firstengagement surface.
 10. The apparatus of claim 9, wherein an exteriorsurface of the cylindrical body is flush with an exterior surface of theplug.
 11. The apparatus of claim 10, wherein the plug includes a step,an end of the retainer collar to be received in the step.
 12. Anapparatus comprising: a valve body defining a fluid flow passagewaybetween an inlet and an outlet; a cage disposed in the fluid flowpassageway; a plug disposed in the cage; a retainer collar coupled at anend of the plug, the retainer collar including a second aperture toreceive the end of the plug, an exterior surface of the retainer collarincluding a first engagement surface having a first non-circularcross-section; and an anti-rotation collar coupled at an end of thecage, the anti-rotation collar having a second engagement surfacedefining a first aperture to receive the retainer collar, the firstaperture having a second non-circular cross-section, the engagementsurfaces to interact to inhibit rotation of the retainer collar and theplug; and a third aperture defined by the plug, the second and thirdapertures being coaxial, the third aperture to receive a stem and thesecond aperture to surround the stem.
 13. The apparatus of claim 12,wherein the first engagement surface and the second engagement surfaceinclude corresponding flat surfaces that interact to inhibit rotation ofthe retainer collar relative to the anti-rotation collar.
 14. Theapparatus of claim 2, wherein the first engagement surface or the secondengagement surface includes splines and the other of the firstengagement surface or the second engagement surface includes grooves toreceive the splines to inhibit rotation of the retainer collar relativeto the anti-rotation collar.
 15. The apparatus of claim 12, wherein thefirst engagement surface or the second engagement surface includes aslot and the other of the first engagement surface or the secondengagement surface includes a protrusion to be received by the slot toinhibit rotation of the retainer collar relative to the anti-rotationcollar.
 16. The apparatus of claim 12, wherein the retainer collarincludes a cylindrical body and a flange extending from the cylindricalbody, the flange defining the first engagement surface.
 17. Theapparatus of claim 16, wherein an exterior surface of the cylindricalbody is flush with an exterior surface of the plug.
 18. The apparatus ofclaim 17, wherein the plug includes a step, an end of the retainercollar to be received in the step.
 19. The apparatus of claim 12, wherethe retainer collar includes a first transverse bore and the plugincludes a second transverse bore, a fastener disposed in the first andsecond transverse bores to couple the plug and the retainer collar. 20.The apparatus of claim 19, wherein the retainer collar defines a grooveinto which a seal is to be disposed, the first transverse boreintersects the groove at an opening of the first transverse bore. 21.The apparatus of claim 20, wherein an interaction between the seal andthe groove is to retain the seal relative to the retainer collar and theplug.
 22. The apparatus of claim 20, wherein the seal is to cover theopening of the first transverse bore.
 23. An apparatus comprising: afirst collar to be coupled to a plug, an exterior surface of the firstcollar having a first keyed surface, an interior surface of the firstcollar to at least partially surround the plug; a second collar to becoupled to a cage, the second collar defining an aperture, the apertureat least partially defined by a second keyed surface, the second collarto receive the first collar, the first keyed surface to interact withthe second keyed surface to inhibit rotation of the first collarrelative to the second collar; and a pin disposed in a first transversebore of the first collar and a second transverse bore of the plug, thepin to couple the first collar and the plug, the cage defining a secondaperture to receive and slidably guide the plug, an interaction betweena seal and the cage to substantially prevent fluid flow between the sealand the cage and to align the first collar relative to the cage.
 24. Theapparatus of claim 23, further including a valve, the second collar tobe disposed within a fluid passageway of the valve.
 25. The apparatus ofclaim 23, wherein the first keyed surface includes one or moresubstantially flat surfaces and the second keyed surface includes one ormore substantially flat surfaces.
 26. The apparatus of claim 23, whereinthe first keyed surface includes opposing first flat surfaces to engagerespective opposing second flat surfaces of the second keyed surface,the opposing first and second surfaces to inhibit rotation of the firstcollar relative to the second collar.
 27. The apparatus of claim 23,wherein the second collar includes an internal flange defining thesecond keyed surface.
 28. An apparatus, comprising: a valve bodydefining a fluid flow passageway between an inlet and an outlet; a cage;a plug disposed in the cage; a plug collar coupled at an end of theplug, an exterior surface of the plug collar having a first non-circularcross-section; and a cage collar coupled at an end of the cage, the cagecollar defining an aperture having a second non-circular cross-section,the plug collar disposed in the aperture, an engagement between theexterior surface of the plug collar and an interior surface defining theaperture to prevent rotation of the plug as the plug moves relative to avalve seat to control fluid flow between the inlet and the outlet,wherein the plug collar includes a first transverse bore to intersect asecond transverse bore of the plug, a fastener disposed in the firsttransverse bore to enable the plug and plug collar to move togetherrelative to the cage and cage collar, wherein an opening of the firsttransverse bore defines a groove surrounding the plug collar, a sealdisposed within the groove to prevent fluid flow between the cage andthe plug collar.
 29. The apparatus of claim 28, wherein the aperture isa first aperture and the plug includes a second aperture, the first andsecond apertures being coaxial, a stem being received within the secondaperture, the first aperture surrounding the stem.
 30. The apparatus ofclaim 28, wherein the plug collar includes a flange, the flange having afirst keyed surface corresponding to a second keyed surface of the cagecollar, the second keyed surface disposed in the aperture.
 31. Theapparatus of claim 30, wherein the first keyed surface and the secondkeyed surface include interacting flat structures to prevent rotation ofthe plug collar relative to the cage collar.